Left ventricular dysfunction, from any cause, leads to cardiac remodeling and changes in gene expression resulting in the progressive myocyte and pump dysfunction that characterize heart failure. This study is designed to determine whether supplemental thyroid therapy, in euthyroid patients, affects the expression of myosin heavy chain and beta adrenergic receptor genes in the failing heart. This study includes monitoring for changes in cardiac function that could occur in response to hormone supplementation and upregulation.